1. Field of the Invention
This invention relates to a semiconductor device, and more particularly, to a multi-chip package type semiconductor device in which more than one IC chip can be packaged.
2. Description of the Related Art
In the related art, there are several types of multi-chip packages in which more than one IC chip can be packaged. One typical multi-chip package is a stack type multi-chip package that packages at least two IC chips in a stacked manner.
In the stack type multi-chip package, the semiconductor device includes an insulating substrate, a first semiconductor chip formed on the insulating substrate and a second semiconductor chip, which is formed on the first semiconductor chip. Each of the semiconductor chips includes terminal pads, and the insulating substrate includes internal terminals. In the stack type multi-chip package, the terminal pads of the first semiconductor chip are connected to the internal terminals by a first conductive wire, and the terminal pads of the second semiconductor chip are connected to the internal terminals by a second conductive wire. The insulating substrate, a first semiconductor chip and a second semiconductor chip are encapsulated by a sealing material, such as resin.
According to the stack type multi-chip package structure, since the second semiconductor chip is mounted on the first semiconductor chip, the distance between one of the terminal pads on the second semiconductor chip and one of the internal terminals, which is closest to the second semiconductor chip, is longer than that between one of the terminal pads on the first semiconductor chip and one of the internal terminals, which is closest to the first semiconductor chip. Therefore, the second conductive wire that connects the terminal pad of the second semiconductor chip to the internal terminal should be longer than the first conductive wire that connects the terminal pad of the first semiconductor chip to the internal terminal.
When the semiconductor device including conductive wires having the different lengths is encapsulated by the sealing material, the second conductive wire that is longer than the first conductive wire is pushed by injection pressure from the sealing material. As a result, the second conductive wire may contact an adjacent conductive wire so that circuits of the second semiconductor chip may short.